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I have a new house with all Pella windows including (2) 6’x6’ picture windows. On only one of these windows I get a circle of condensation in the middle of the window about 18” in diameter every day. It is on the inside and not between the panes . It is very strange because it comes in the exact middle of the window and is a circle or sometimes an oval. It does not matter if the shade is left down or up and it occurs independent of the heat being on or off. Any ideas on what may because this? I understand condensation and what causes it but the fact that is a circle in the middle of the window has me stumped. is it possible the window is defective in some way? see attached pic

I have a new house with all Pella windows including (2) 6’x6’ picture windows. On only one of these windows I get a circle of condensation in the middle of the window about 18” in diameter every day. It is on the inside and not between the panes . It is very strange because it comes in the exact middle of the window and is a circle or sometimes an oval. It does not matter if the shade is left down or up and it occurs independent of the heat being on or off. Any ideas on what may because this? I understand condensation and what causes it but the fact that is a circle in the middle of the window has me stumped. is it possible the window is defective in some way? see attached pic

clean off the former big yellow circle pella label/sticker/decal glue. try cooking oil first then a solution of dish detergent (not dishwasher) and water. if that doesn't work try rubbing alcohol then window cleaner. the glue insulates the room side of the glass keeping it cooler then the rest that's why you're getting condensation there in that shape.

Tnx for the tip but I don't think that's it. there is no residue or glue or anything else on the window. it is perfectly clean...you can even run a razor blade scraper over it and nothing comes up or off.

then maybe you've had a low-E film failure or have a low-E film defect creating a cold spot in the center of the picture window. if your windows are under warranty i'd call Pella to come investigate.

if it gets too hot or cold on one spot on the window it might crack the glass or cause a seal failure too.

if you have a vaporizer or humidifier pointed at the window or an aquarium or fountain under it or a HVAC vent or radiator air valve nearby you'd have said so. you sure one of the family members (or pet?) isn't standing on that bench and breathing a circle of condensation on that cold window in the morning before you observe the circle of wetness? do you have a spot light aimed right at the center of the picture window that might temporarily heat up the spot on the window at some point before you see the circle of condensation? no chance an external vent like a HVAC exaust or dryer exaust or bathroom or cooking vent exaust somehow blowing on the outside of the window eariler and heating up the center of the window either?

in the meanwhile you could get a little fan and circulate air near the window. they even have battery operated ones with little suction cups with exposed flexable fan fins that can't cut little fingers.

clean off the former big yellow circle pella label/sticker/decal glue. try cooking oil first then a solution of dish detergent (not dishwasher) and water. if that doesn't work try rubbing alcohol then window cleaner. the glue insulates the room side of the glass keeping it cooler then the rest that's why you're getting condensation there in that shape.

My bet is the gas in between the panes is not working properly to insulate the window. Could be a bad mixture, not enough, failed seal, etc. Usually you would see this as the windows age and the seals fail. We have an Andersen slider and the stationary side has developed this same issue in the last couple years, although it is 16 years old, not new like yours. Our pattern is more like a rorschach ink blot test, though, not a nice circle like yours.

Just had a thought while typing....I wonder if the panes of glass are bowed toward each other ever so slightly so that there is less space between them in the middle and thus less insulating gas there. Try putting a straight edge diagonally across the inside and outside panes to see if there is a gap in the middle. I am going to try that with my slider!

On January 13th, we had a new picture window installed in our home. It is made by Arcor and the center pane is approximately 6x6. We have the exact same issue (identical as yours with a very distinct round circle condensing on the inside, not in between the panes). We live in Canada and it is cold now but we monitor our humidty and it sits around 41% which should not leave any significant condensation on the windows. None of our other windows in the home have any condensation issues at all nor did the window we had replaced with this new one. We are waiting to hear from Arcor's service department.

I am very interested to hear how you resolved it. Please see the picture below.

I've seen similar patterns where the installer has used their suction cup "handles" to hold onto the window while installing it. It leaves behind oils from the rubber. Also, as a previous poster mentioned, there can still be adhesive residue left behind from the manufacturer's sticker, even though it's not obvious and you've cleaned the glass.

First, try to find a product called De-Solv-It. It's the best citrus solvent I've found, and it does an excellent job of removing oils and adhesives where other products fail. It will leave it's own oily film behind, but you can easily clean that off with some other cleaning product. It's kind of expensive and hard to find: around $8 for a 12 oz. bottle. WalMart used to carry it, but the last place I found it was the local Ace Hardware store.

Try some vinegar. Sometimes a little bit of acid helps to break down stubborn residues, especially if it's minerals bonded to the glass.

If that doesn't work, try a mild abrasive designed for removing water spots off of glass. You can usually find this at auto parts stores.

Captjackny, The problem, more than likely, is that the glass inside is touching the outside piece, that is why you are getting the circle of condensation. The transference of cold is causing the moisture. This is not uncommon in a large piece of glass like the one you have. You need to call the warranty people from Pella and tell them you have a glass failure. They will either "pump up" the piece of glass you have, to get the two pieces away from each other or replace the glass completely. If you bought the windows with gas in them make sure they pump it up with gas or demand a replacement. I spent 37 years in the window industry and this is usually the cause in this situation. If it were moisture from the house you would have condensation all over the window.